The fabrication of modern circuits typically involves several steps. Integrated circuits are first fabricated on a semiconductor wafer, which contains multiple duplicated semiconductor chips, each comprising integrated circuits. The semiconductor chips are then sawed (or diced) from the wafer and packaged. The packaging processes have two main purposes: to protect delicate semiconductor chips, and to connect interior integrated circuits to exterior connections.
In packaging processes, a semiconductor die (or chip) is mounted on a package component using flip-chip bonding. An underfill is dispensed into the gap between the semiconductor die and the package component to prevent cracks from being formed in solder in bumps or balls, wherein cracks are typically caused by thermal stresses. Underfill also reduces delamination at dielectric interface. The package component is an interposer that includes metal connections for routing electrical signals between opposite sides. The die is bonded to the interposer through direct metal bonding, solder bonding, or the like. The package component may also be other types of substrates. There are many challenges in die packaging.